RTFM…
or Read the F—ing Manual is a familar acronym in the tech business. But most people don’t like to read manuals (f—ing or otherwise) to extract information. They want to know how to accomplish tasks. Occasionally, they want to know why you did something in a particular way (mostly as it pertains to not being able to accomplish a task).
A nice approach to quickly creating useful documentation which addresses the “How Do I …?” questions that customers frequently have is ScreenSteps. They have a couple of short videos on their home page which explain the concept (basically, a nice framework for making screenshots and annotating them), and a 30-day free trial.
At $40 bucks (the Pro version with some extras is $60), it’s a cheap solution to a common (and vexing) problem.
If you’re getting a lot of support calls, or you want a better way of documenting your products and services, I recommend taking a look at Plan not to plan, which outlines how small businesses can use ScreenSteps.